The invention relates to an electrolysis plate having an outer non-conductive frame, in particular made of a fiber-reinforccd cresol resin, an electrically conductive, bipolar graphite plate which is mounted therein and is preferably slotted on both sides and, in the region of the electrolyte feed, has plastic skirts, dimensioned to force the direction of electrolyte solutions, located in the region of the electrolyte feed. The invention further relates to electrolysers made with such electrolysis plates.
Known electrolysers such as hydrochloric acid electrolysers, have electrolysis plates in the form of frame elements which carry electrically conductive, bipolar graphite plates which function as anode/cathode. Such constructions are disclosed by the publication DT 23 27 883. The frame elements are generally arranged in blocks of typically 32 or 38 plates and thus form a unit as an electrolyser having 31 or 37 electrolysis cells for the electrolysis of, for example, hydrochloric acid to give chlorine gas and hydrogen gas, which are operated at current intensities of up to 4800 A/m2. The hydrochloric acid is passed through the frames, starting from conduits in the lower region of the frame elements via specially arranged boreholes, in each case on the anolyte side or the catholyte side, in each case from the bottom into the anolyte space or catholyte space respectively, and removed again in the upper region of the frame elements together with the gases generated via exit boreholes into upper conduits of the frame elements.
Known electrolysis elements are supplied, depending on the current intensity, with 130 l/h to 180 l/h of anolyte acid and catholyte acid. The hydrochloric acid at 60-80xc2x0 C. meets the diaphragm separating the anolyte space from the catholyte space and is randomly distributed, after deflection, for example, at the diaphragm over the slots in the graphite or at the channel between frame and graphite plate.
In the case of the known construction of the electrolysis elements, operating faults occur owing to the loading and possibly destruction of the diaphragm, in particular, in the area of the electrolyte ingress into the anolyte space or catholyte space.
The object of the invention is to provide an electrolysis element which avoids the disadvantages of the known construction and has a comparatively longer service life.
The object is achieved of the invention by protecting the anolyte side and catholyte side of an electrolysis element with a plastic skirt. The plastic skirt is generally an inert film, particularly, a film made of polyvinyl difluoride or a polyfluorocarbon to protect the diaphragm or the membrane from chemical, thermal and mechanical corrosion due to the anolyte jet and catholyte jet incident from the boreholes present in the electrolysis element.
The invention relates to an electrolysis plate comprising (a) an outer non-conductive frame; (b) an electrically conductive, bipolar graphite plate that has an electrolyte feed and that is mounted to the non-conductive frame and (c) plastic skirts that are located in the region of the electrolyte feed and that are dimensioned to force the direction of electrolyte solutions. The invention is also directed to an electrolyser containing such electrolysis plates.